Ratiometric Fluorescent Glucose Sensor Based On Near Infrared Emitting Polymer Dots

Continuous monitoring of glucose has always been a research hot in biomedical fields.Optical method such as absorptiometry,fluorescence,and surface plasmon resonance are minimally invasive,even noninvasive,which has been regarded as an ideal way for sensing glucose.However,these optical sensors have not had the clinical success of electrochemical methods for point-of-care testing because of the limited performance.Here,we proposed a ratiometric fluorescent glucose sensor based on nearinfrared emitting polymer dots.The optical sensor combines oxygen-sensitive polymer dots(Pdots)with glucose oxidase that sensitively detect glucose when oxygen is consumed in the glucose oxidation reaction.By reasonable choice of oxygen insensitivity near-infrared dye and oxygen sensitive phosphorescent dye,the glucose sensor we designed has a visible excitation and near-infrared emission.The sensor has a good response to glucose in vivo.This sensor has the potential to be applied to the detection of glucose metabolism in deeper tissues such as tumors.The main research contents are as follows:(1)Aqueous dispersion of semiconductor polymer dots were prepared by using a reprecipitation method.Glucose oxidase was connected to the nanoparticle surface by bioconjunction,forming a glucose sensor with near-infrared emission.Size,zeta potential,absorption and emission spectra were characterized.Experimental results show that the glucose sensor has good stability and excellent optical properties.(2)We evaluated the responsivity of the glucose sensor to different concentrations of glucose solution.Experimental results indicate that the fluorescence of 753 nm was sensitive to glucose concentration,while the fluorescence of 605 nm remained constant.The constant fluorescence and the sensitive near-infrared phosphorescence lent themselves to ratiometric sensing,which improved the accuracy of the sensor.The ratio of emission peak from 753 to 605 nm showed a linear relationship with the glucose concentration,which is useful for applications such as the quantitative determination of tissue glucose levels.The sensor has a good specificity because of enzyme nature.(3)We evaluated the response of sensor in vivo by whole animal biophotonic imaging.The sensor after subcutaneous implantation provides a luminescence signal that is transdermally detectable and the brightness of about 750 nm closely responsive to blood glucose fluctuations.